Mac - Android online/offline problem

I have a Mac which works flawlessly with spotify and a Samsung Galaxy SII Skyrocket that shows all songs but only about 5% of the songs EVERYWHERE will it let me listen to. i tried plugging my phone into the computer and it started "downloading" the songs but then stopped 16% of the way through for some reason and won't start back up. i Don't know if it has anything to do with it, but i also can't figure out how to get "online" so i'm always "offline" right now.